SU828365A1 - Method of converting dc voltage into sinusoidal ac voltage - Google Patents

Description

one

The invention relates to a converter technique and can be used to obtain a controlled sinusoidal output voltage in autonomous voltage inverters.

A known method of converting a constant voltage to an alternating one is to convert the supplying constant voltage into three additional constant voltages at different levels, forming a stepped voltage from an additional constant voltage with a sinusoidal envelope of the required frequency and extracting the first harmonic. Converting a DC power supply to additional DC voltages is usually accomplished by converting the DC voltage to AC high frequency, transforming it, and converting AC high frequency to the required number of additional voltages of different levels. This method of converting DC to AC is relatively complex 1.

There is also known a conversion method in which the duration of high-carrier frequency voltage pulses is modulated, for example, by a sinusoidal law 2.

The closest solution to the technical essence and the achieved result to the invention is a method of converting a constant voltage into an alternating sinusoidal one, which consists in converting a constant voltage into a sequence of high-frequency polarized pulses, transforming them into high frequency pulses.

frequency in the signal with the sinusoidal envelope of the desired frequency, the selection of the first harmonic. Signal formation of the required frequency in this method is carried out by rectifying high-frequency pulses at the half-period of the output frequency and changing the polarity of the rectified pulses at the other half-period. The sinusoidal law of variation of the envelope is obtained by excluding certain pulses from the overall sequence in the frequency conversion unit 3.

Regulation of the output voltage is carried out by eliminating different

the number of pulses from the overall sequence, however, this leads to a deterioration in the harmonic composition of the output voltage. In addition, the exclusion of part of the pulses from the overall sequence

impairs the use of block elements

converting a DC signal into a high frequency and high frequency transformer.

The aim of the invention is to improve the spectral composition of the output voltage and to improve the utilization of converter elements.

The goal is achieved by the fact that in the known method of converting a constant voltage into an alternating sinusoidal one, including converting a constant voltage into a sequence of high-frequency heteropolar impulses, transforming them, changing the polarity of the pulses at each half-period of the ARM frequency and forming a sinusoidal envelope - the formation of a sinusoidal envelope is carried out by modulating the duration of the pulses. a high frequency according to a sinusoidal law.

The method of converting a constant voltage into a sequence of high-frequency pulses, the duration of which varies according to a sinusoidal law, makes it possible to regulate the output voltage by proportionally varying the duration of all pulses with little or no change in the frequency of the output voltage meter. The use of all high-frequency IM1 pulses excludes the work at idle of the unit — converting the DC voltage into a sequence of different polarity pulses and a high-frequency transformer, which improves their use.

FIG. 1 shows a converter that implements the proposed method; in fig. 2 - the algorithm of operation of the keys 6 of block 1 and the keys 7 of block 3.

The device contains a DC voltage conversion unit 1 in a sequence of different high-frequency pulses, a high-frequency transformer 2, a high-frequency signal conversion unit 3 into a signal with a sinusoidal envelope of the required frequency, an advantageous filter 4, a control system 5, keys 6-7.

At the input of the comparator unit 5, the control signal t / y and the reference signal Uon (Fig. 2, a) are received, and the control signal varies sinusoidally.

In those moments when the control signal

equal to the reference signal, the device is switching. The impulses of the system 5 sets the algorithm of operation of the keys 6 of block 1 (Fig. 2, b, c) and the keys of block 7

3 (Fig. 2, d, d). From the above algorithm (Fig. 2, bd) it can be seen that transformer 2 operates at a high frequency (Fig. 2, e), and the signal at the output of block 3 has a sinusoidal frequency envelope of the output voltage (Fig. 2, g) . When forming the output voltage envelope, all transformable pulses having the same polarity are used in the half period.

The output voltage is controlled by varying the amplitude of the control signal at a constant frequency. In this case, there is a proportional change in the width of all pulses and, consequently, the amplitude of the envelope.

Thus, the pre-modulation of the high-frequency AP-sivi sinusoidal signal allows to improve the spectral composition of the output voltage

at regulation, and use of elements of the converter.

Claims (3)

Invention Formula A method for converting a DC voltage into a sinusoidal alternating voltage, which involves transforming a DC voltage into a sequence of high-frequency, alternating pulses, transforming them, changing the polarity of the pulses at each half-period of low frequency and forming a sinusoidal envelope, characterized in that, in order to improve the spectral composition of the output voltage curve and improve the use of converter elements, the formation of the sinusoidal envelope is carried out by modulating the duration of high frequency pulses under the sinusoidal law. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 316162, cl. H 02M 7/52, 1971. 2. Sandler A.S., Gucius Yu. M. Thyristor Inverters with Pulse Width Modulation, M., Energia, 1968, p. 14, fig. 2.1. 3. Patent of France No. 2357101, cl. Н 02Р 13/18, 1975. + 0g -five. X. . 7 .